Many buildings require large access openings to permit the ingress and egress of large equipment, merchandise or flow of people into and front the structure. Covering these large openings requires large doors. Different types of doors have been developed to cover such openings, such as top or bottom slidably mounted doors supported by a roller/track system, vertically pivotally mounted doors or top pivotally mounted (overhead) doors. Various means exist for opening and closing these doors, including man power, cables or hydraulics.
If a door opening is proportionately large with respect to the building size and there is limited available lateral space front the sides of the door opening or limited space in front of the door opening, many of these doors become impractical. Specifically, vertically pivotally mounted doors for large openings have a large arc of rotation and require significant forward or lateral space front the door opening when the doors are in the open position. Top slidably mounted doors require significant lateral extension of the horizontal support track(s) from the door opening to support the door when moved to an open position. Further, vertically pivotally mounted and top slidably mounted doors may interfere with other building operations or attributes. For example, an opaque vertically pivotally mounted or top slidably mounted door in an open position may extend in front of building viewing windows next to the door opening, blocking the view. Although transparent glass doors could be utilized, glass is quite heavy, historically requiring significant structural support for the door.
Top pivotally mounted, single panel doors are preferred, almost required, where lateral space is limited or non-existent. However, these doors still require significant space in front of the door opening to be opened. Further, these doors are susceptible to wind damage because they typically present a large impervious surface when extended in the open position, and can be damaged in strong winds.
Top pivotally mounted single panel doors also require significant structural support because they are heavy and leveraged out front of a building. Historically, the materials used on a top pivotally mounted single panel door panels are typically of light weight to address structural support issues. Transparent glass panels for such doors are historically impractical because of the enhanced weight of glass and structural support requirements.
A great deal of force is typically required to open and close top pivotally mounted single or bi-fold panel doors because of the door weight and structural support required for these doors. To aid in the opening and closing of these doors, hydraulic cylinders have been employed.
By way of example, U.S. Pat. No. 6,883,273 to Kerkvliet discloses a top mounted single panel door pivotally secured by an upper edge to a header of a building door opening so that the door can be rotated outward from the building to an open position. The door is opened and closed by a pair of hydraulic cylinders. A first end of each hydraulic cylinder is pivotally secured to a building door jamb or frame and a second end of each hydraulic cylinder is pivotally secured at a side edge of the door, about half way down the side of the door. The action of the cylinders puts significant stress on the building frame where the cylinder is mounted.
Another example of a single panel hydraulically operated door is shown in Publication No. U.S. 2011/0232196 to Robinson. This patent application discloses a number of support trusses secured to the inside of the single panel door in spaced relation along the width of the door. The trusses extend from the top to the bottom of the door. The trusses are required to give the single panel door stability and strength and prevent it from bending under its own weight or from being damaged in high wind conditions. However, adding the trusses adds weight to the door, requiring greater structural support to hold the door open. Although hydraulic cylinders are used to open and close the door, because of the mounting orientation of the hydraulic cylinders and the size of the door, Robinson requires very long and powerful hydraulic cylinders to open and close the door.
A version of a hydraulically operated top pivotally mounted/overhead door that has reduced susceptibility to wind damage and reduced extension from the building is a bi-fold door. One such hydraulically operated bi-fold door is disclosed in Applicant's U.S. Pat. No. 7,814.957. Two hydraulic cylinders mounted on opposite sides of the door frame are used to open and close the overhead door. A first end of each hydraulic cylinder is pivotally mounted to the building door frame (the “building mount”), interior from and below the axis of rotation defined by the mounting hinges securing the upper panel of the door to the building door frame. A second end of each cylinder is attached to a side edge of the upper panel. In a door closed position, the hydraulic cylinders extend downward and forward from the building mount to a position close to the bottom of the top pane of the bi-fold door.
U.S. Pat. No. 5,020,580 to Dalman discloses a hydraulically actuated bi-fold door with the hydraulic cylinder and structural support mounted on the outside of the door to help reduce the force required to open (lift) the door. This exposes all the hydraulics to the elements. It also requires an extremely long hydraulic. The force imparted by the hydraulic cylinders when opening the door is communicated to the ground and not to the building. The door also includes a leveling mechanism that causes the lower bi-fold panel to fold horizontally and adjacent to the upper panel when the door is in its opened position. However, the upper panel of Dalman, in the open door position, is angled back towards the building structure. In a rainfall, the water is directed back towards the building, which is a detraction.
UK Patent Application GB 2150965A to Hindley discloses an overhead bi-fold door that is opened or closed with hydraulic cylinders. Both the external mount system of FIG. 1 and the internal mount system of FIG. 4 disclose the hydraulic cylinder positioned above the axis of rotation of the upper panel of the bi-fold door which requires significant addition vertical building space in the structure to house the cylinders. The cylinders must be long to effectuate opening and closing of the door. Further, the exterior mount version of the door shown in FIG. 1 has the same failing as Dalman—the upper panel of the door directs rain into the building when the door is in the open position.
There remains a need for an easily installed hydraulic operated door system that requires no space lateral of the door opening and limited space in front of the door opening for the door to open, that absorbs many of the load forces created from opening and closing the door within the door system, and that requires smaller, less expensive hydraulic cylinders to open and close a door even with heavy, non-traditional door panels, such as panels composed of glass.